Random access memory (RAM) is a ubiquitous component of modern digital architectures. RAM can be a standalone device, or can be integrated in a device that uses RAM, such as a microprocessor, microcontroller, application specific integrated circuit (ASIC), system-on-chip (SoC), and other like devices. RAM can be volatile or non-volatile. Volatile RAM loses its stored information whenever power is removed. Non-volatile RAM can maintain its memory contents even when power is removed. Although non-volatile RAM has advantages, such as an ability to retain stored information without applied power, conventional non-volatile RAM has slower read/write times and consumes more power than volatile RAM.
There is increasing market demand for integrated circuits, such as system on a chip (SoC) processors, which include embedded non-volatile memory (NVM) (e.g., an eFlash memory). Embedded NVM memory can be used to store sophisticated feature-rich software and firmware for long periods of time, and also provides quick programming and erasing of data. Conventional embedded NVM is an example of a type of multiple-time programmable (MTP) memory.
One type of conventional NVM memory is a charge-trapping silicon-oxide-nitride-oxide-silicon (SONOS) transistor having a feature size of 65 nm. The charge-trapping SONOS transistor stores data by trapping a charge in the nitride layer (i.e., the “N layer” in “SONOS”). This technology requires multiple masks to fabricate, which leads to high fabrication costs that are ultimately passed on to consumers. The conventional charge-trapping SONOS transistor technology also has fabrication process restrictions that limit advancements in feature size reduction. For example, the fabrication process restrictions (e.g., gate space restrictions) prevent the conventional charge-trapping SONOS transistor technology from being fabricated using 20 nm SoC and 16 nm FET advanced technologies. There are currently no MTP memories available in advanced technologies, such as 20 nm SoC and 16 nm FET advanced technologies, which do not have excessive costs associated with development and fabrication.
Accordingly, there are long-felt industry needs for methods and apparatus that improve upon conventional methods and apparatus, including the improved methods and apparatus provided hereby.